Local Physics Grid

Is there a way to implement a local physics grid? Here are the details:

• There is always a global physics grid (what we have right now in unity).
• In addition to that I want to create a local grid. A local grid will have a parent. This can be either a global grid or another physics grid
• The local physics update will come after the parent's physics update.
• Any objects in the local grid will not collide with anything else besides its parent and siblings.
• This is basically like a hierarchy system in unity, however it handles rigid bodies in children objects

I feel like this is a good approximation to simulate large vehicles to walk around. However with limited exposure to the physics engine, I can't think of a way to implement this.

 

I don't think this is possible using Unity physics. In Unity, two rigidbodies belong to the global physics grid even if they're parented.

I'm not sure if even PhysX would support that feature. Looking at the PhysX docs I found no reference to such grid system. I'd say it's unlikely that Unity support that feature if PhysX doesn't offer it.